package com.my.map;

import java.util.HashMap;

/**
 * @author marshal
 * @version 2021-06-02
 */
public class MapTest {
    public static void main(String[] args) {
        var map = new HashMap<>();
        map.put(null, null);
        // 只会添加一次，会覆盖上一条语句
        map.put(null, null);
        map.put(0, null);
        map.put(1, "one");
        map.put("USA", "America");
        System.out.println(map.get(0));
        System.out.println(map.get(null));
        System.out.println(map.get(10));
    }
}
